Circuit breaker of fluid immersed type having pair of series connected interrupters



K. H. DATE FLU 3,200,223 G PAIR ID IMMERSED TYPE HAVIN 5 Sheets-Sheet l Aug. 10, 1965 CIRCUIT BREAKER OF OF SERIES CONNECTED INTERRUPTERS Filed Nov. 15, 1962 K. H. DATE 3,200,223 FLU PAIR 3 Sheets-Sheet 2 Aug. 10, 1965 CIRCUIT BREAKER OF ID IMMERSED TYPE HAVING OF SERIES CONNECTED INTERRUPTERS Filed Nov. l5, 1962 5m( MM Jrrmwfy,

3,200,223 PAIR K. H. DATE FLU Aug. l0, 1965 CIRCUIT BREAKER OF ID IMMEHSED TYPE HAVING OF SERIES CONNECTED INTERRUPTERS 3 Sheets-Sheet 3 Filed Nov. l5. 1962 v/L-m. 5.

Ilfjh INVENTOR Kaza@ H. 2471s www@ 4free/vir United States Patent O ananas on raum nvnviEnsEn TYPE sEurEs coNNEorEn ENTER- RUPrEns CIRCUIT BREAKER HAVENG PAIR F Wis., assigner to This invention relates to circuit interrupting devices and more particularly to circuit interrupting devices of the liquid immersed type.

In the interruption of a capacitive load, large transient over-voltages are sometimes produced. During the switching of such capacitive loads the current is initially interrupted at the iirst current zero with relatively little diiiiculty because the load remains at approximately the crest value of the instantaneous voltage of the source for a short time during which there is relatively little voltage across the circuit breaker interrupting contacts. However, one-half cycle after the first current zero, the voltage of the source is reversed to its crest value so that a voltage of approximately double the crest value appears across the circuit breaker' contacts asa recovery voltage. During this time the arc is likely to restrike across the partially separated circuit breaker contacts. Restrikes of this nature, being of an oscillatory character, may produce serious high over-voltages in the system.

An object of the invention is to provide a circuit interrupting device capable of interrupting capacitive currents as well as normal load currents.

lt is another object of the invention to provide a circuit interrupter for use in capacitive switching in which the buildup ot dielectric material between the parted circuit breaker contacts is more rapid than the buildup or" voltage thereacross.

A more specific object of the invention is to provide a circuit breaker having a pair of series connected interrupters in which one of the interrupters parts prior to the iirst current Zero for affecting the initial interruption and in which the second interruptor parts subsequent to the iirst current zero or within a short time thereof so that the second interrupter will provide a substantially ion and other particle free dielectric gap for the prevention of restrilte during the relatively high voltage surges which follow.

These and other obiects and advantages of the instant invention will become more apparent from the detailed description thereof taken with the accompanying drawings in which:

FlG. l is a side elevational View of the interruptor incorporating the instant invention;

FIG. 2 is a side elevational view with parts broken away or" a portion of the interrupter shown in FIG. l;

FiG. 3 is a view taken along lines 3 3 or FIG. l;

FiG. 4 is a view taken along lines 4-4 of FG. l; and

FIG. 5 shows a plot of the contact separation of the device depicted in FIG. l.

Referring now to the drawings in greater detail, the current interruptor according to the instant invention is shown to be of the low oil type which includes an insulating housing 1d of porcelain or other dielectric material. The housing 1li is supported on a metallic base 11 to which a lead wire (not shown) may be connected. The base l1 is provided with an upstanding flange l2 which deiines a socket for surrounding the lower end of the housing lil and to which it is cemented by `a low temperature melting alloy 13. A gasket 17 between the bottom surface of porcelain housing lli and the metallic base 11 hermetically seals the lower end of housing lil.

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A contact operating mechanism enclosure 14 is disposed at the upper end or" the housing 10 and has a similar depending tiange 15 which is cemented at 16 to the upper end of the housing it). It will be understood that the enclosure 14 is fluid tight and contains an operating mechanism of any well known type which will cause a movable contact rod 18 to execute substantially straight line axial movement, but only one actuating link 19 thereof is illustrated for the sake of brevity. For a more complete disclosure of such a contact rod operating mechanism, reference is made to Patent No. 2,838,638 to K. H. Date and assigned to the assignee of the instant invention.

The interior cylindrical bore Ztl of the insulating housing 19 constitutes a iluid reservoir filled with dielectric iluid 21 to a level indicated by dashed lines 22. A plurality of apertures 23 are provided in the lower end of the housing 14 for the purpose of permitting expansion of dielectric fluid into the housing 10i during current interruption and for facilitating restoration of the normal fluid level by draining fluid back into the interior of housing lil when the circuit interruptor is inactive.

The contact rod 1S is shown to comprise an upper conductive section Sii, a lower conductive section 31 and an intermediate non-conductive section 32, which joins the conductive sections 3i? and 31. The conductive sections Sil and 31 may be composed of aluminum for lightness and for this reason has a tip 33 of arc resistant material such as copper tungsten. The non-conductive portion 32 may be of epoxy resin. f

A pair of insulating tubes 34 and 34 surround the contact rod i8 and are ailixed in a coaxial endwise relation by a pair of channel members 37, a conductive stud 38 and a bolt 39. The upper tube 34 has a pair of opposed cutaway portions 35 intermediate its ends to expose the upper conductive portion 39 of the contact rod to the dielectric iiuid 21 within the housing 1t). An arc interrupting chamber Se is disposed intermediate the ends of the lower tube 3ft and surrounds the lower conductive portion 31 of the contact rod 1S. The conductive stud 38, which is positioned intermediatet he cutaways 35' and the interrupting structure 36, performs the function of supporting contact assemblies 40 and 42 which Vbridge the non-conductive portion 31 of the contact rod 18 when the latter is in a closed position and also provide a current path between these contact assemblies.

A stationary wiping contact assembly 44 is disposed below the metallic housing 14 and in the upper end of the tube 34 for slidably engaging the upper conductive portion Sti of the contact rod 1S. Mounted on the metallic base il and extending upwardly into the lower end of the tube 3d is a stationary Contact and dashpot assembly t5 engageable by the lower conductive portion 31 of rod l.

The contact assembly 44 includes a set of wiping contact fingers 46 pivotally supported on an annularly grooved conductive post d8 which depends from the metallic enclosure 14 and which has an axial bore 47 for slidably receiving the rod 1li. The lingers 45 are biased radially toward engagement with the contact rod portion Sil by tensional garter springs 49.

As seen in greater detail in FIG. 2, the contact assembly 42, which slidably engages the lower contact rod conductive portion 31, similarly includes an annularly grooved axially bored conductive post 50 depending from the stud 38 and a plurality of contact fingers 52 biased toward engagement with the contact rod 18 by garter springs 54. A similarly shaped conductive post 55 extends upwardly from the stud 33 and carries a pair of outwardly ared and upwardly extending contact fingers 56 which carry contact members 57 at their upper ends and which are biased by springs 58 toward engagement with a pair of contact elements 59 which are carried at the outer ends of a transversely extending conductive adapter 60 aixed to the lower end of the contact rod conductive portion 30. It can thus be seen that the point of engagement between the members 57 and the elements 59 is at a point displaced radially from the surface of the contact rod 18. This insures that when the interrupter is opened the arc does not erode the non-conductive portion 32 of the rod 18 upon the separation of the contact rod portion 30 from thel contact assembly 40. v

The lower contact and dashpot assembly includes a conductive stud 62 affixed to the base plate 11 and Yhaving a central bore 63 for receiving a hollow contact post 65. A plurality of contact fingers 66 are pivotally mounted on the Contact post 65 and urged into high pressure engagement with the contact r-od 18 by springs 68. A piston 70 is reciprocally received within the post 65 and is urged upwardly by a coil spring 72 into engagement with an overhanging stop 73 formed by the tips 74 of contact iingers 66. A check valve consisting of a ball the contact fingers 66. A check valve consisting of a ball 76, a seat 77 and an aperture 78 is disposed in the lower end ofthe post 65. In addition, an aperture 80 is formed in the stud 62 to place the bore 63 in communication with the dielectric iluid 21 in the insulating housing 10.

It will be appreciated that when the movable contact rod 18 moves into its closed position it will impact the piston 70 which absorbs the kinetic energy from the Contact rod 18. This energy forces the piston 70 to move downward slightly as a portion of the dielectric fluid trapped below it leaks along its sides. The spring '72 then returns the piston 70 to its initialposition as more fluid is drawn through the apertures 70 and 78 and past the ball check 76. In addition, it will be appreciated that because of the position of the aperture 8@ in the stud 62 and of the aperture 78 in the lower end of the post 65 `no sludge or small metal particles will be drawn below the piston 70.

The details of the arc interrupting chamber 36 forms no part of the instant invention. It will suffice for the purposes of the present disclosure to note that chamber 36 consists of a plurality of plates 82 of an insulating material which are joined in a stacked relation in any convenient well known manner and each of which has a central aperture 83 (see FIG. 4) for receiving the contact rod 18. 82 also has a plurality of fluid duct apertures 84 which intersect and are spaced circumferentially around the central aperture 83. It can be seen, therefore, that the apertures 83 of the plates 82 cooperate to form a continuous central bore 85 through the chamber 36 and the apertures 84 form continuous fluid ducts 86 which surround and open into the bore S5. A plate 87 having a single aperture is disposed at the upper end of the chamber 36 for closing the upper end of the ducts 86. While the ducts 86 are shown to be straight it will be understood that the discs 82 may be so arranged that they present other types of paths such as a spiral. The tube 34 is provided with a pair of apertures 88 adjacent the contact assembly 45 for venting the bore 85 and the ducts 86 of chamber 36. For a more complete description of the interrupter 36 and its method of operation, reference is made to US. Patent No. 2,886,673 to A. Van Ryan and assigned to the assignee of the instant invention.

- It can --be seen from FIG. that the overlap of the contact lfingers 56 `and the contact members "59 is ysubstantially greater than that ofthe contact rod portion 31'and the contact fingers 66. For example FIG. 5 shows thev plot of contact travel against elapsed time in cycles for one particular embodiment of the invention. Here it can be seen that the contact rod 18 will have moved upwardly approximately 3A after lthe parting of the lower contacts 31-66 before Ythe upper contacts 56-59 part. This difference in overlap is designed, taking into con- Each of the platesY sideration the acceleration of the contact rod, so that the contact members 59 will remain in engagement with the contact fingers 56 until approximately one hal-f cycle after the separation of the rod portion 31 from the contact fingers 66. This will insure that the upper contacts 56-59 will part either subsequent to or immediately before the current goes through its rst zero and is interrupted by the lower contacts 33-66. As a result there will either be no arc struck at the upper contacts 56459 or the arc will be so short in length and duration that little contamination of the oil therearound will result.

The operation ofthe interrupter accordi-ng to the invention will now be discussed with reference to FIGS. l and 5. During the interruption of a capacitive current, the operating mechanism (not shown) will begin moving the contact rod 18 upwardly. This willvdisengage the lower contact rod portion 31 from the contact fingers 66 whereby an arc will be drawn ltherebetween. As the current passes through its rst zero the interrupting structure 36 will have little difficulty interrupting the arc. However, as illustrated in FIG. 5, the contact members 59 and the contact fingers 56 will be so proportioned that they will stay in engagement during all or substantially all of this initial movement of the contact rod 18.

' After the current passes through its first zero the voltage across the interrupter will build up rapidly. This rapid buildup or" voltage would normally cause a restrike of the arc at the lower contacts 31-66 due to the presence of ionized particles and other products of arc interruption existing in this gap as a result of the initial interruption. However, the separation of the upper contacts 56 59 has now occurred to provide a relatively uncontaminated gap in series with the lower contacts 31-66. In addition because the contact rod 18 is now at a steeper portion of the displacement curve of FIG. 5 the uncontaminated gap at the upper contacts 56-59 is lengthening faster than the voltage buildup across the device. As a result there is no restrike across the interrupter.

rlhus, it can be seen that even though the initial contact rod movement is insuflicient to provide enough contact separation to prevent restrike after the first half cycle during the interruption of a capacitive current, the provision of a second interrupter in series, which remains closed during substantially all of the arcing across the rst interrupter, will provide a sufiiciently rapid dielectric buildup to prevent such restrike.

While only a single embodiment of the invention has been shown and described, it is intended that the invention be limited only by the scope of the appended claims.

I claim: Y

1. A circuit interrupter of the iluid immersed type comprising an insulating housing containing a quantity of dielectric Huid, iirst and second stationary contact means disposedwithin said housing in spaced apart relation, a contact rod having rst and second conductive portions and an intermediate nonconductive portion and being movable longitudinally into and out of a closed position relative to said rst and second stationary con tact means, said lirst and second conductive portions being in overlapping engagement with said lirst and second stationary contact means, respectively, when said contact rod means is in its closed position, said iirst and second conductive portions and said first and second stationary contact means being operative to provide a series current path when said Contact rod means is in its closed position, the degree of overlapping engagement between said second conductive portion and said second stationary contact means being substantially greater than between said first conductive portion and said first stationary contact means so that said second stationary contact means will remain in engagement with said second conductive portion until said rst conductive portion has separated a substantial distance from said first stationary contact means.

2. A circuit interrupter of the fluid immersed type comprising an insulating housing containing a quantity of dielectric fluid, first and second stationary contact means disposed in spaced relation within said housing, an elongate member having first and second conductive portions and an intermediate nonconductive portion and being movable into and out of a closed position relative to said first and second stationary contact means, said first and second conductive portions being in overlapping engagement with said rst and second stationary contact means respectively when said elongate members is in its closed position, said first and second conductive portions and said iirst and second stationary contact means being operative to provide a series current path when said elongate member is in its closed position, an arc extinguishing device disposed adjacent said first stationary contact means and having a passageway in which said elongate member is adapted to reciprocate, the overlapping engagement between said second conductive portion and said second stationary contact means being substantially greater than that between said first conductive portion and said first stationary contact means so that said second conductive portion will remain in electrical engagement with said second stationary contact means until said first conductive portion has separated a substantial distance from said first stationary contact means as said elongate member moves out of its closed position, said second stationary contact means being directly exposed to said dielectric fluid.

3. A circuit interrupter of the fiuid immersed type comprising, an elongate insulating housing containing a quantity of dielectric fluid, first and second stationary contact means disposed within said housing in spaced apart relation, a Contact rod mounted for longitudinal movement within said housing and comprising a pair of conductive portions and an intermediate non-conductive portion, one of said conductive portions being movable into and out of overlapping engagement with said first stationary Contact means, said other conductive portion overlappingly engaging said second stationary Contact means, said second stationary contact means bridging said nonconductive portion when said contact rod is in its engaged position to provide a series current path, the overlapping engagement between said other conductive portion and said second stationary Contact means being substantially greater than that between said first conductive portion and said first stationary contact means so that said second stationary contact means will remain in engagement with said other conductive portion until said one conductive portion has separated a substantial distance from said first stationary contact means.

4. A circuit interrupter of the fiuid immersed type comprising, an insulating housing containing a quantity of dielectric fiuid, first and second stationary contact means disposed in spaced relation within said housing, an elongate contact member mounted for longitudinal movement within said housing and having a pair of conductive portions and an intermediate non-conductive portion, each of said conductive portions being movable into and out of overlapping engagement with a different one of said first and second stationary contact means, said second stationary contact means bridging said non-conductive portion when said contact rod is in its engaged position to provide a series current path, an arc extinguishing device disposed adjacent said first stationary contact means and having a passageway in which said elongate contact member is adapted to reciprocate, the overlapping engagement between said second stationary contact means and one conductive portion being substantially greater than that between the other conductive portion and said first stationary contact means so that said second stationary contact means will remain in electrical engagement with said one conductive portion until said other conductive portion has separated a substantial distance from said first stationary Contact means, said second stationary Contact means being directly exposed t0 said dielectric fiuid.

5. A circuit interrupter of the fini-d immersed type comprising an insulating housing containing a quantity of dielectric fluid, first and second stationary contact means disposed in spaced relation within said housing, an elongate member mounted for longitudinal movement into and out of a closed position relative to said first and second stationary contact means and including first and second conductive portions and an intermediate nonconductive portion, said rst and second conductive portions being in overlapping engagement with said first and second stationary contact means respectively when said member is in its closed position, said second stationary contact means including contact members spaced radially from the sur-face of said elongate member, said second conductive portion including radially spaced contact elements `for overlapping engagement with said contact members, said first and second conductive portions and said first and second stationary contact means being constructed and arranged to provide a Iseries current path when said elongated member is in its closed position, an arc extinguishing device disposed adjacent said first stationary contact means and having an zaxial passageway in which said elongate member is adapted to reciprocate, the degree of overlapping engagement between said contact elements and said contact members being substantially greater than between said first conductive portion and said first stationary contact means, so that said second stationary contact means will remain in electrical engagement rwith said second conductive yportion until said `first conductive portion has separated `a substantial distance -from said first stationary contact means.

6. A circuit interruptor of the fluid immersed type comprising an elongate insulating housing containing a quantity of dielectric fliuid, `first and second stationary contact means disposed in spaced relation within said housing, movable contact rod means comprising a pair of conductive portions and an intermediate nonconductive portion and 4being movable between open and closed position relative to said first and second stationary contact means, one of said conductive por-tions slidably engaging said second stationary contact means and the other conductive portion engaging said first stationary contact means when said contact rod means is in its closed position, said second stationary contact means bridging said nonconductive portion when said contact rod means is in its closed position to provide a series current path between said first and second stationary contact means, said one conductive port-ion and said second stationary contact means remaining in sliding engage-ment Iuntil said con-tact rod means has moved -a substantial distance out of its closed position and after said other conductive portion has moved out of engagement with said first stationary contact means.

7. A lcircuit interrupter of the fluid immersed type comprising an elongate insulating housing containing a quantity of dielectric fluid, first and second stationary contact means disposed in spaced relation within said housing, :a contact rod comprising a pair of conductive portions and intermediate nonconductive portion, said contact rod being movable between open and closed positions relative to said first and second stationary contact means, one of said conductive portions slidably engaging said second stationary contact Imeans and the other conductive por-tion being in engagement with said first stationary contact means when said contact rod is in it closed position, said second stationary contact means bridging said nonconductive portion when said contact rod is in its closed position to provide a series current path between said first and second stationary contact means, an arc extinguishing device ldisposed adjacent said first stationary contact means and having an axial passage-way in which said contact rod is adapted to reciprocate, said one conduct-ive portion and said second stationary contact means remaining in sliding engagement until said contact rod has moved a substantial distance out of 4its closed position and after-said otherrcon-V an intermediate nonconductive portion, said contact rod means being movable between open and closed positions vrelative to said first and second stationary contact means, one of said conductive portions slidably engaging said second stationary Contact and the other conductive portion being in engagement with said first stationary contact `when said contact rod means is in its closed position,

said second stationary contact means bridging said non-` conductive portion when said contact rod means is in its closed position to provide a series current path between said first and second stationary contactV means,`

said-second stationary contact means including contact members spaced radially lfrom the surface of said contact rod means, said one conductive portion including radially spaced contact elements for slidabily engaging said contact mem-bers, said contact elements and said contact members remaining in sliding engagement ifor a substantial distance as said contact rod moves out of its closed position and after said other conductive por-tion has moved out of engagement with said first stationary contact means.

9. A circuit interrupter of the fluid immersed type comprising, an insulating housing containing a quantity of dielectric fluid, first :and second stationary contact means'disposed in spaced relation within sa-id housing, a Contact rod including first and second conductive portions and an intermediate nonconduotive portion and being mounted for longitudinal movement into'and out off' a closed position relative to said first and second stationary contact means, said first and second conductive portions being in overlapping engagement with said first and sccond stationary contact means respectively when said contact rod is in its closed position, said second contact Y means bridging -said intermediate nonconductive portion when said contact rod is in its closed position to provide a series current path between said first and second stationary contact means, said second stationary contact means including contact members spaced radially from the surface of said second conductive portion, said contact rod'including radially spaced contact elements for overlappingly engaging said contact members, the overlapping engagement between said contact elements and said contact members being Isubstantially greater than that between said contact rod and said first stationary contact meansY so that said second stationary contact means will remain in electrical engagement with said contact rod until said rod has separated a substantial distance Afrom said first stationary contact means.

lib. A circuit interrupter of the liuid immersed type comp-rising, an elongate insulating housing containing a quantity of dielectric fluid, first and second stationary contact means disposed in spaced'relation within said housing, a contact rod mounted for longitudinal movement into and out of la closed position relative to -said first and second stationary contact means `and having a pairvof conductive portions and an intermediate non- Vconductive portion, one of said conductive portions being in overlapping engagement with said lfirst stationary contact means when said contact rod is in its closed position, said lsecond stationary contact means including contact members spaced radially from the surface of said contact rod, the other of said conductive portions including radi- :ally spaced Contact elements for'overlapping-ly engaging 4said contact members when said contact rod is in its closed position, said second stationary contact means bridging said non-Conductive portion when said contact rod is in its engaged position lto provide a series current path through said housing, yan arc extinguishing device disposed adjacent said first .stationary contact means and having an axial passageway in whichV said contact rod is adapted to reciprocate, the overlapping engagement between said contact elements and said contact members being substantially greater t-han that between said one conductive portion and said first stationary contact means sothat said second stationary contact means will remain in electrical engagement with said contact elements until said one conductive portion has separated a substantial distance from said first stationary contact means, said second lstationary contact means being directly exposed to said dielectric fluid.

lll. A circuit interrupter of the fluid immersed type comprising, an elongate insulating housing containing a quantity of dielectric iiuid, a first stationary cxmtactV disposed adjacent one end of said housing, second and third stationary contacts disposed intermediate the ends of said housing and electrically connected to each other, a contact rod mounted for axial movement into and out of a closed position relative to said Ifirst and third stationary contacts and comprising a pair of conductive por-tions and an intermedi-ate non-conductive portion, one of said conductive pontions slidably engaging said second stationary contact and being in overlapping engagement with said Ifirst stationary contact when said cont-ac-t rod is in its closed position, said third station-aryV contact including contact members spaced radially from the surface of said contact rod, the other of said conductive portions including radially spaced contact elements movable into and out of overlapping engagement 'with said Contact members when said Contact rod moves intoand out of its closed position, said second and third stationary contactsy bridging said non-conductive portion vwhen said contact rod is in its engaged position to provide a series current path between said first and second stationary contacts, an arc extinguishing device dispose/:l between said first and second stationary contacts and having an axial passageway in which said contact rod is adapted to axially reciprocate, the overlapping engagement between said contact elements and said contact members being substantially greater than that between said Contact rod and said first stationary contact `so that said third stationary contact -will remain in electrical engagement with'said contact rod until said rod has separated a substantial distance from said first stationary contact, s-aid third Vstationary contact being directly exposed to said dielectric fluid.

r12,. A circuit interrupter of the fluid immersed type comprising an elongate insulating housing containing a quantity of dielectric iiuid, iirst and second stationary contact means dispose-d in spaced apart relation within said housing, contact rod means mounted for longitudinal movement between open and closed positions relative to said first and second stationary contact means, said contact rod means including first and second conductive portions and an intermediate nonconductive portion, said Ifirs-t and second conductive portions being mov-able into and .out of engagement with said first and second stationary contact means respectively as said contact rod means moves between its closed and open positions, said second conductive por-tion and said second stationary conta-ct means being in sliding engagement for a predetermined portion of the movement of said contact rod 'means out of its closed position and after said first conductive poition has disengaged from said first stationary contact means', said firstand second conductive portions and said first and second stationary contact means' providing -a series current path when said contact -rod means is in its closed position.

said housing, a contact rod mounted for longitudinal ,movement between open and closed positions relative to said first and second stationary contact means, said contact rod having first and second spaced yconductive por- -t-ions and an intermediate nonconductive portion, said tirst and second conductive pontions being movable into rand out `ot engagement with said :51st and second stationary contact means respectively as said contact rod lmoves between its open and closed positions, said second conductive portion and said second stationary contact means including means for maintaining the electrical engagement therebetween -until said first .conductive portion has moved a substantial distance out of engagement 10 with said first stationary Contact means, said rst and secon-d conductive portions and said first and second stationary Contact means providing -a seriesI current path when said Contact rod is in its closed position.

References Cited by the Examiner UNITED STATES PATENTS 2,533,774 1/51 Friedrich et al 20G-145 2,677,740 5/54 Allard 20G-145 2,897,325 7/59 Nijland 20G-150 ROBERT K. SCHAEFER, Acting Primary Examiner. KATHLEEN H. CLAFFY, Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,200,223 August 10, 1965 Kazuo Henry Date It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 7, line 3, after "stationary", first occurrence, insert Contact Signed and sealed this 22nd day of February 1966.

SEAL) lttest:

ERNEST W. SWIDER EDWARD I. BRENNER Lttesting Officer Commissioner of Patents 

1. A CIRCUIT INTERRUPTER OF THE FLUID IMMERSED TYPE COMPRISING AN INSULATING HOUSING CONTAINING A QUANTITY OF DIELECTRIC FLUID, FIRST AND SECOND STATIONARY CONTACT MEANS DISPOSED WITHIN SAID HOUSING IN SPACED APART RELATION, A CONTACT ROD HAVING FIRST AND SECOND CONDUCTIVE PORTIONS AND AN INTERMEDIATE NONCONDUCTIVE PORTION AND BEING MOVABLE LONGITUDINALLY INTO AND OUT OF A CLOSED POSITION RELATIVE TO SAID FIRST AND SECOND STATIONARY CONTACT MEANS SAID FIRST AND SECOND CONDUCTIVE PORTIONS BEING IN OVERLAPPING ENGAGEMENT WITH SAID FIRST AND SECOND STATIONARY CONTACT MEANS, RESPECTIVELY, WHEN SAID CONTACT ROD MEANS IS IN ITS CLOSED POSITION, SAID FIRST AND SECOND CONDUCTIVE PORTIONS AND SAID FIRST AND SECOND STATIONARY CONTACT MEANS BEING OPERATIVE TO PROVIDE A SERIES CURRENT PATH WHEN SAID CONTACT ROD MEANS IS IN ITS CLOSED POSITION, THE DEGREE OF OVERLAPPING ENGAGEMENT BETWEEN SAID SECOND CONDUCTIVE PORTION AND SID SECOND STATIONARY CONTACT MEANS BEING SUBSTANTIALLY GREATER THAN BETWEEN SAID FIRST CONDUCTIVE PORTION AND SAID FIRST STATIONARY CONTACT MEANS SO THAT SAID SECOND STATIONARY CONTACT MEANS WILL REMAIN IN ENGAGEMENT WITH SAID SECOND CONDUCTIVE PORTION UNTIL SAID FIRST CONDUCTIVE PORTION HAS SEPARATED A SUBSTANTIAL DISTANCE FROM SAID FIRST STATIONARY CONTACT MEANS. 